RHCSA Practical Lab Series – Configuring Cron Jobs

🔍 Lab 5: Automating Tasks with Cron Jobs

📌 Objective

In this lab, you will:

✔ Enable and verify the cron daemon (crond)
✔ Schedule a cron job for user jack to run a command daily at 14:23
✔ Verify the scheduled task execution

📌 Step 1: Ensure Cron Service is Running

🔹 Check if crond is active:

[root@node1 ~]# systemctl status crond

🔹 If the service is not running, start and enable it:

[root@node1 ~]# systemctl enable --now crond

📌 Tip: The --now flag ensures that crond starts immediately and remains enabled after reboots.

📌 Step 2: Schedule a Cron Job for User jack

🔹 Edit the cron jobs for user jack:

[root@node1 ~]# crontab -e -u jack

🔹 Inside the crontab editor, add the following line:

23 14 * * * /usr/bin/echo "Automated task executed" > /home/jack/cron_output.log 2>&1

📌 Explanation:

• 23 14 * * * → Runs the command every day at 14:23 (2:23 PM)
• /usr/bin/echo "Automated task executed" → Prints a test message
• > /home/jack/cron_output.log 2>&1 → Saves output and errors to a log file

✅ If added successfully, the job is now scheduled!

📌 Step 3: Verify the Scheduled Cron Job

🔹 List all cron jobs for jack:

[root@node1 ~]# crontab -l -u jack

🔹 Expected Output:

23 14 * * * /usr/bin/echo "Automated task executed" > /home/jack/cron_output.log 2>&1

✅ If the entry appears, the job has been correctly scheduled.

📌 Step 4: Validate Execution

🔹 After the scheduled time (14:23), check the log file:

[root@node1 ~]# cat /home/jack/cron_output.log

🔹 Expected Output:

Automated task executed

✅ If this output appears, the cron job is working!

📌 Troubleshooting:

• Ensure user jack is allowed to use cron (/etc/cron.allow or /etc/cron.deny should not block the user).

If the job does not run, check the cron logs:

[root@node1 ~]# journalctl -u crond --since "15 minutes ago"

✅ Final Summary

✔ Enabled and verified the cron service
✔ Created a cron job for jack to execute at 14:23 daily
✔ Confirmed that the cron job executes correctly and logs output

📌 Next Lab: Configuring a Shared Directory with Group Ownership

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